Electric-current-controlling device



April 1, 1924. 1,488,788

J. F. HEARN ELECTRIC CURRENT CONTROLLING DEVICE Filed Nov. 8, 1919 /n wn M r; I John I? Hear/7.

Patented Apr. 1, 1924.

UNITED STATES PATENT OFF-ICE.

JOHN F. HEARN, OF PASSAIC, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COM-PANY, INCORPORATED, OF NEW YORK,1\T. Y., ACOR-PORATIO'N OF NEW YORK.

ELECTRIC-CURRENT-CONTROLLING DEVICE.

Application filed November 28, 19-19. Serial No. 341,151.

To all whom it may concern:

Be it known that I, JOHN F. HEARN, a citizen of the United States,residing at Passaic, in the county of Passaic, State of New Jersey, haveinvented certain new and useful Improvements inElectric-Current-Controlling Devices, of which the following is a full,clear, concise, and exact description.

This invention relates generally to electric circuit controllingdevices, and more particularly to selective switches for use inautomatic systems.

The invention has for its object to provide a switch of the automaticselective type in which the weight of the moving part shall becompensated.

In its preferred embodiment the invention i applied in the form of aselector switch to an automatic telephone system. The selector switchhas movable brush rods carrying brushes arranged to wipe over acommutator plate, and wipers arranged to engage contacts of a terminalbank by means of which, connections may be established. Friction rollersare provided to impart motion to the brush carrying rods. The number ofbrushes and wipers carried by the rod has usually been about five. Itwill be seen that if the same rod and rollers are used to carry agreater number of brushes and wipers, say fifteen or more, the tendencyis for the friction roller to slip unles this additional weight iscompensated for in some manner. This invention provides a means forcompensating for this weight. The particular compensating meansdisclosed possesses advantages in that it is compact, simple and has anegligible mass in its moving parts.

The drawing illustrates an embodiment of the present invention.

In the drawing, the rod 1, supported by and sliding in guides in theframe plates 11 and 32 carries the brush 3 which i adapted to contactwith the contacts on the commutator bank 5. Rod 1 also carries thewipers 2, which contact with the terminals in banks 1. At the lower endof rod 1 is attached a flat stiff metal strip 6 passing between theconstantly rotating friction rollers 7 and 9 and the rollers 16 and 15.Roller 7 and 9 revolve on the shafts 8 and 10 respectively in thedirections indicated by the arrows.

Rollers 16 and 15 revolve freely on the shafts 33 and 34.

The shaft 33 is supported by the bell crank 13, which is hinged on thepin 35. The other end of the bell crank 13 extends in front of the polepieces of electromagnet 11 and is adapted to be drawn up against themagnet, thereby forcing the roller 16 against the strip 6. The pressureof the roller 16 against the strip 6 pushes the strip 6 against thefriction roller 7 and an up ward motion in the rod 1 is therebyproduced.

Similarly a downward motion is produced by the roller 9, when theelectromagnet 12 draws the arm of the bell crank 14 upward.

The crank 14 hinged on the pin 36 forces the roller 15 to engage thestrip 6 with the roller 9.

The frame 25 is fastened by means of screws 28 to a portion of the mainframework 27. Attached to the frame 25, by means of an adjusting bolt 29having the nut 30 and lock nut 31, is a coil spring 26. A flexibleribbon 24 is attached at one end to the spring 26 and is wound about thespiral drum 23 and fastened to it by the screw 37 Drum 23 is adapted torevolve about the shaft 22 supported by the frame 25. Circular pulley 20also revolves on shaft 22 and is fastened to the drum 23 so as torevolve therewith. A second ribbon 19 is fastened at one end by screw 21to the circumference of the pulley 20 and adapted to wind thereon. Theother end of the ribbon 19 is attached by means of a clamp 18 to thebrush carrying rod 1.

The tension in the spring 26 varies directly with its extension. It maybe adjusted by means of the bolt 29 and the ad justing nut 30 and locknut 31.

The spiral drum 23 is made of such a form that its radius at the pointof tangency varies inversely with the extension of the spring 26. Itwill be seen that the force exerted at the circumference of the pulley20 and in the ribbon 19 is therefore constant and equal for allpositions of the rod 1.

\Vhat is claimed is:

1. In a circuit controlling device, the coin bination of a movablecircuit controlling member, means for varying the position thereof, andmeans to exert a uniform force on said circuit controlling member tocompensate forits Weight, whereby said circuit controlling member isadapted to remain in its adjusted position.

2. In a circuit controlling device, the combination of a movable circuitcontrolling member; means for varying the position thereof, andretractile spring means to uniformly compensate for the weight of saidcircuit controlling member in all positions 10 thereof.

In witness whereof, I hereunto subscribe my name this 25th day ofNovember, A. D., 1919.

JOHN F. HEARN.

